1. Field of the Invention
The present invention relates to a linear light emitting apparatus. Specifically, the invention relates to an improvement in a light emitting apparatus which converts the light of a light source to linear light using a light guide member and then emits the linear light.
2. Description of the Related Art
Conventionally, a linear light emitting apparatus using a linear light guide member has been used for lighting and the like. When light is guided into the linear light guide member, normally, the amount of the light arriving in the portion of the linear light guide member distant from a light source is reduced when compared with the amount of the light in the portion of the linear light guide member existing in the vicinity of the light source. This gives rise to the uneven amount of the light, with the result that the light provides uneven light. To solve this problem, there have been conducted various studies. For example, in Japanese Patent No. 2900799, there is disclosed a lighting apparatus in which light is guided in from the end face of a linear light guide member, the light is reflected by the reflecting surface of the upper surface of the linear light guide member, and the resultant linear light is then emitted from the lower surface of the linear light guide member. According to this lighting apparatus, on the upper surface reflecting surface of the linear light guide member, there are disposed at given intervals light expanding and reflecting portions each having a uniform shape, or there are disposed at given intervals light expanding and reflecting portions in such a manner that they broaden gradually as they part away from a light source, thereby enhancing the light reflecting and expanding effect of the lighting apparatus. Further, to compensate the reduction of the amount of light arriving in the portion of the linear light guide member existing distant from the light source, the linear light guide member is narrowed as it parts away from the light source. As other conventional technologies, there are known the linear light emitting apparatus that are disclosed in JP-A-2005-114894 and JP-A-2005-300852.
In the conventional linear light emitting apparatus, by enhancing the light expanding and reflecting action in an area distant from the light source, a light take-out efficiency in the area distant from the light source is enhanced to thereby reduce the uneven amount of the light emitted. However, when compared with the area near to the light source, in the area distant from the light source, the amount of the light reaching there is itself small. Therefore, in some cases, simply by enhancing the light expanding and reflecting action in the area distant from the light source, the reduction of the uneven light emission amount cannot be attained sufficiently. The longer the linear light guide member is, the greater this tendency is. On the other hand, when the light expanding and reflecting portions are widened as they part away from the light source, or when the linear light guide member is narrowed as it becomes distant from the light source, the width of the linear light is varied accordingly. That is, it is impossible to obtain the linear light that has a uniform width.